Article synchronizing conveyer



Jan. 29, 1963 FlSK Filed March 9, 1959 2 Sheets-Sheet 1 (0( @0 5 Q /2 Z ;/4 Q/M 33 34 4/ m 5 \E 1:; my 24 INVENTOR 2 Sheets-Sheet 2 Filed March 9, 1959 PULSE PULSE TIME ARTICLE REACHES CHECK POINT INVENTOR. ROBERT FISK Y BY M WW A TTORNEYS United States Patent Ofifice 3,075,630 PatentedJan. 29, 1963 3,075,630 ARTICLE SYN CHRONIZING CGNVEYER Robert W. Fisk, Sunnyvale, Calif., assignor to Mathews Conveyor Company, Ellwood City, Pa., a corporation of Pennsylvania Filed Mar. 9, 195%, Ser. No. 798,214 12 Claims. (Cl. 198-76) This invention relates to conveyor systems for distribution of articles and particularly concerns systems in which articles are positioned at selected locations on a moving conveyor element.

In automatic distribution systems, article manipulating devices are frequently operated when a specific location on a moving conveyor element reaches the manipulating device. Unless the article is properly positioned with respect to such specific location, the article manipulating device may be operated prematurely or belatedly with a resulting improper manipulation of the article or even failure of the article manipulating device to properly engage an article. For example, a pusher for removing selected articles from a conveyor may be actuated when a certain point on the moving conveyor element passes a fixed point at the pusher element. If the article is in advance or behind the selected location, the pusher element may improperly engage the article or fail to engage it.

A major object of this invention is to provide apparatus for exactly positioning articles at selected locations on a continuously moving conveyor element. More specifically, an object of this invention is to provide a conveyor system with a synchronizing conveyor element for properly positioning articles with respect to selected locations on a continuously moving conveyor in the system.

Another object of this invention is to provide a speed control for a conveyor element efiective to adjust the speed of the conveyor so regardless of the time when an article is placed on the conveyor element it is moved to a particular location a fixed period of time after reception of a signal.

In the attainment of these objects, an important feature of the invention resides in the arrangement of a variable speed conveyer normally moving at a velocity corresponding to the velocity of a continuously moving conveyer and decelerated upon the arrival of an article at a selected point on the synchronizing conveyer. This deceleration is continued until a signal is generated according to the position of a selected location on the continuously moving conveyer with respect to the discharge end of the synchronizing conveyer. Then, deceleration is arrested and the synchronizing conveyer is accelerated to the speed of the continuously moving conveyer to discharge the article on to the continuously moving conveyer when the selected location arrives at the discharge end of the synchronizing conveyor. Synchronization is accomplished by assuring that the terminal or discharge velocity of the synchronizing conveyor is equal to the velocity of the continuously moving conveyor. Preferably, this is effected by delaying acceleration of the synchronizing con-.

veyor for a time interval corresponding to the diiference between a minimum or zero velocity of the synchronizing conveyor and the velocity at which deceleration of the synchronizing conveyor is arrested when a signal is received from the continuously moving conveyor.

Another important feature of this invention resides in the operation of a speed controller for a conveyer element to decelerate the conveyer element from a maximum velocity in response to the arrival of an article at a selected position. This deceleration of the conveyer element is discontinued by a signal and the conveyer element is accelerated to its maximum velocity after a time delay period corresponding to the difference between the decelerated velocity and a minimum or zero velocity. Operation of the speed controller is efiected by a first piston which shifts the speed controller to decelerate the con- Veyer element and a second piston which shifts the speed controller to accelerate the conveyer element after the desired time interval. An article on the conveyer element causes a shifting of the second piston to its minimum velocity position at which it is spaced fromthe speed controller element and supplies a metered flow of fluid to the first piston for shifting the speed controller to decelerate the conveyer and move the speed controller toward the second piston. In response to a signal, the supply of fluid to the first piston is cut oif and a metered flow of fluid is supplied to the second piston. The velocity of the conveyer element remains constant until the second piston reaches a point corresponding to the decelerated velocity where it operates the speed controller to accelerate the conveyer element to its maximum velocity.

Other objects, advantages and features of the invention shall become apparent from the following specification and accompanying drawings, wherein:

FIG. 1 is a diagrammatic view of a conveyer system embodying the invention in its preferred form and showing schematically a speed control for a synchronizing conveyer;

FIG. 2 is a circuit diagram of electrical controls for the system;

FIG. 3 is a velocity versus time diagram showing the operation of the system when the acceleration signal arrives after the article stops; and

FIG. 4 is a velocity versus time diagram showing the operation of the system when the acceleration signal arrives before the article stops.

As illustrated in FIG. 1, random spaced articles are conveyed on a continuously moving conveyer 11, which may be a belt conveyer, driven at a substantially constant speed by a motor 12 to transfer the articles one at a time onto a synchronizing conveyer 13. Synchronizing conveyer 13 is driven by a variable speed motor 14 for depositing the articles equally spaced at selected locations on a vconveyer 15 continuously driven by a motor 16. Conveyer 15, which may be a belt conveyer, carries the articles past a series of article manipulating devices (not shown) which are actuated automatically when certain selected locations of the continuously moving conveyer 15 pass such manipulating devices. Unless the articles are exactly positioned at the selected locations on the continuously moving conveyer 15, the manipulating devices will be operated according to the position of the selected locations on the-conveyer and may improperly engage or even fail to engage an article which should be in that selected location.

In order that articles will be properly positioned in the selected locations on conveyer 15, the speed of motor 14 is controlled to vary the speed of synchronizing conveyer 13 so each article on synchronizing conveyor 13 is discharged onto a selected location of conveyer 15.

This variation in the speed of motor 14 is controlled so the synchronizing conveyer 13 is normally moved at a maximum velocity corresponding approximately to the velocity of conveyers 11 and 15. When an article is transferred from conveyer 11.onto synchronizing conveyer 13, a sensing device such as photoelectric cell 18 is actuated to produce a signal which causes deceleration of motor 14. When a selected location on conveyer 15 reaches a certain position determined with respect to the ates a signal generator or switch 22 to discontinue deceleration of the motor 14 and the synchronizing conveyer 13. At the same time actuation of switch 22 starts an ac-- celeration cycle, which, after a time delay corresponding to the difference between the velocity of conveyer 13 at the time deceleration is arrested and a minimum velocity or .zero .velocity' for .conveyer .13 causes acceleration of the motor14 so conveyerTlS transfers -an .article .onto conveyer 15 a fixed time interval after operation of switch 22 generatesa signal. Since .switch..22 is .always operated according to therelative .position of a vselected location on, conveyer 15 and .the discharge end of .conveyeri 13, the same time interval always .elapses from the generation of the signal "by switch, .22 until the selected location of conveyer 15 is -positioned to .receivean article from conveyer 13. By using the sametime interval to discharge, an article from conveyer.13, .the article is always discharged 7 onto the-selected location. of conveyer 15.

Motor'14 may be a hydraulic motor thespeed of which iscontrolledby alspeed controller or throttle valve 23 to'which fluid under pressure is conducte'd'fromv a supply 24. Speed control va1ve,23.may be shifted by :a piston ro'd'25, on afirst fluid actuated piston .26 in adirection to reducethefiow of pressure'fluid to motor 14 and thereby decelerate the motor. ,.Movement..of.thespeed-control valve'23, ina direction-to increase, the .flow offluid to motor 14 and,therebyacceleratethe.motor andsynchronizing conveyer 13, may be ,efiectedrbythrottle valve acceleration control rod 29 .arranged'to'be engaged'by piston rod 27 on a secondfiuid .operatedpiston28. .Pistons'26 and 28 are reciprocated within cylinders 26a and 28a. respectively.

"When an article on conveyer 13, which is normally moving at its maximum velocity, actuates .a sensing device :or atp'hotoelectr'ic cell I8,-.contacts,.31 (FIG...2) .are c'losed'to energize coil'32 of solenoid 33 for control valve 34. This shifts valve,34lin,a;direction to supply fluid underj'fiillv pressure through a, conduit 35 to. shift piston 28 tothe right as shown iniFIGVJ, sandv therebymove rod 27- to its minimum velocity. position. At the same time, fluid pressure'jfrom supply .24 is conducted through valve '34 to; meterin-g valve'3fitfornmoving piston-26 at a fixed ratelin a directionioshift valve 23 in adirection to deceleratemotor '14 and synchronizing conveyer13.

This deceleration continues .at lag-fixed rate until the selected location on conveyer .15 reaches a predetermined position withrespectto the dischargeend .of conveyer 13 whereupon tracking cam 21 operatessignal generating switch "22.. to.close contacts' 38 and. energize coil 39 of; solenoid 41"to reverse .valve,.34. Simultaneously contacts42 of switch '.22.-are ,openeduto de-energize coil 32 of solenoid'33. .This reversingof valves 34 cuts .off the flow of Ifiuid'topiston 26,.and openspiston Mind the rod-end ,o'f pistonr28to atmosphere through vent 43. Fluid exhausted fromcylinder 26a passes .freely through check valve I441bypassing metering valve .36.

At the'samejtime, the other end,.of piston .28 is connected to pressure supply 24 through metering valve 45 torsupply-a meteredflow of pressure fluidtormove piston 28 and rod )7 ate uniform velocitytowardihe throttle valve accelerating vcontrol r0629. .Metering valves 36 and .45 .are vset to passilfluid .atfiJbOllt thesame-rate so throttle valve 23 is-shifte'dso the rate of acceleration of motor 14. approximately equals the rate ofdeoeleration off that. motor.

If the valve .34,.remains in. its ,decelerating'position long :enough .for,accelerating control rod. to engage piston rod=27,motor..14 and synchronizing conveyer -13 are decelerated .toa minimum velocity which maybe zero. Thetvelocity of conveyer 13 will remain'at this minimum until .cam 21 actuates switch '22 toreverse valve-34 so the rod 27 v on piston28 .shifts'throttle valve:

acceleration control rod 29 110 accelerate the motor 14 and conveyer 13.

In normal operation; cam 21 actuates:switch"22' while throttle valveuacceleration control. rod1:29 .isispaced from the piston vrodij27. .Thus, when cam'r21 'actuates switch- 22 to reverse valve 34, rod 29 is spaced from piston rod 27 a distance corresponding to a time interval which may be directly proportional to the difference between the minimum or zero velocity for the conveyer 13 and the velocity at which deceleration is arrested. After the lapse of this time interval piston rod 27 moves acceleration control rod29 to shift the throttle valve 23 in a direction .to accelerate the motor 14. Acceleration of motor 14 continues until the valve 23-reaches its maximum velocity position where velocity of motor 14 and conveyer 13 is the same as that of conveyer 15. The total time from the generation of the signal by switch 22 until the article is transferred from conveyer 13 to conveyerlS equals the time necessary for the selected location on conveyer 15 to reach the position to receive an article from conveyer 15. After the article has been transferred to conveyer 15 and another article deposited on synchronizing conveyer 13 actuates photoelectric cell 18, the cycle isrepeated by shifting piston 28 to its minimum velocity position. This shifting is effectedby permitting exhaust fromcylinder 28a through "check valve 47 bypassing metering valve 45.

Under usual operating conditions, when an article is transferred fromconveyor 11, synchronizing conveyor 13 is moving at its maximum velocity. As the article passes photocell 18,-synchronizing conveyor 13 is decelerated below the velocity of distributing conveyor 15 until a selected location on distributing conveyor 15 passes a certain position when cam .21 actuates signal generating switch 22. This opens contacts 42 to deenergize solenoid 33 and closes contacts 38' to energizesolenoid 41 and supply-a meteredflow of fluid pressure to the other side of piston 28. Throttle valve 23 is then movedin a direction to accelerate motor 14 until it reaches its maximum' velocity and the article is transferred from conveyor 13, to conveyor 15.

In this situation the time interval for the selected locationon conveyor 15' to .reacha position toreceive an article arrives at conveyor 15 at the proper time .to

occupy the selectedlocation on that conveyor.

When an'article on conveyor 13 arrives at photoelectric cell 18 .only a short interval before tracking device 21 actuates signal generating-switch 22, the valve 34 will first be shifted to move piston rod 27 to its retracted position and initiate a-dece1erating cycle. Almost immediately, solenoid 41 is energized by the signal from switch 22 to shift the valve 34 to its accelerating position. When this occurs, the velocity of conveyor 13 remains near its maximumin order to transfer the article to the selected location on conveyor 15. This condition existswhen, at the time the article arrives at photoelectric cell 18, the selected location on conveyor-15 is approximately thet same distance ,fromthe transfer point as the photoelectric cell. Thus, the time required for the article to travel from the photoelectric'cell 18 to the transfer point will correspondto that required for vthe selected location on conveyor '15 to travel to the same transfer point.

When an articleonconveyor 13 arrives at the photoelectric' cell considerably before the selected position on conveyor 15 will be ready to receive the article, piston 26 shifts the throttle valve 23 to its minimum velocity or zero velocity position. Conveyor 13 then remains at rest until switch 22'is actuated and acceleration control rod 29 ismoved to shift throttle valve 23 in a direction to: accelerate motor-14. Motor 14 is accelerated until it reaches itsmaximum velocity and then the article is transferred from conveyor 13 to'conveyor 15. In this 'situationthe time interval after actuation of signal genveyor 13 again corresponds approximatelytto the tirne for accelerating piston 28 to move from its;zero velocity;

synchronizing conveyor 13 may be analyzedmathemati,

cally to show that during aitime interval required for synchronizing conveyor 13 -to reach maximum speed at a controlled rate of acceleration, the article on conveyor 13 will have travelled a constant distance vS from the check point, referring to photoelectric cell-18,,after arrival of the signal fromsignal generator 22 Under a condition where the signalfrom signal generator 22 arrives withithe article at the check point, the

speed of the article remains. constant at a velocity;V'.- and the article travels the distance,

FIG.V3 shows a velocity versus time diagram in a situation where the signal generated by. generator 22 arrives after, an article on conveyor 13 (and conveyor 13 stops: In the diagram shownin FIG.-'3,YV=the. velocity at full' or maximum speed, .T=the time to accelerate to: speed.- V from a minimum or zero-velocity. As shown in the diagram of FIG. 3 theyacceleration and deceleration rates areequal, i.e., the slopes ofrthe velocity curves are equal. Under this condition, the distance travelled while stopping equals: 7

. V X T v a p and, the distance travelled while starting equals The total distance 5 'travelled from the checkpoint is' the synchronizing conveyorcorresponds to. thedifference I between "the minimumvelocity of the synchronizing-com -1 veyor and its actual vel ocitywhen the switch '22 is actuated. In this waytheispeediof the synchronizing conveyoris controlled" todeliverthe article-to distributing conveyor a certain period ;of time after switch 22 ;is

actuated;

The embodiment illustrated is .aipreferred the invention. Many modifications of: the invcntion; definedin the appended pclairns-will suggest themselvesto ,those skilled in the art. I

Now consider, the situation where the signal; pulse from signal generator 22 arrives before ,the article and con-- veyer 13.stop. This'situation is shown in the FIG.,4 time versus velocity diagram where ,V =,the .velocity at full speed, V1=the velocity;at time of arrival of the-ssigna l from signal generator-22; flj1=the;,time,period where the article arrives ahead of the pulse from signal generator I 22, T2 is a variable quantity equal tothe timelflk n to acceleratethe article to a speed -V1"fr om rest'and T equals the timeto 'accelerateito-the speedVJfrom rest. It will be noted that T is also the amount of time ;delayrequired before initiation of an acceleration cycle.- Assome that the rates of acceleration anddeceleration-are substantially equal. v I

In all cases, therefore, the delay inacceleration of The distance travelled by the article during the time 1 equ s a 8 (V-ll T1 Y 5 The distance travelled during the time interval T2 equals ('9) j S2=V1 T2 Then the total distance travelled from the check point equals the sum of Since T= T1+T2,:then S=A T for any timeT1 T 0.

What I claim is:

1. Apparatus for positioning articles in selected locations on a continuously moving conveyer element oom 25, prising-a synchronizing conveyer in advance of, the continuously moving conveyer, means actuated by an art1cle on said synchronizing conveyer for decelerating said synchronizing conveyer at a controlled rate of deceleration, and means controlled by the continuously moving conveyer according to the position of the selected location for initiating acceleration at a controlled rateof the synchronizing conveyer to the speed of the continuously mov ing conveyer to transfer the article to the selected location on the continuously moving conveyer. I 2. Apparatus for positioning articles at selected locationson a continuously moving conveyer element coniprising a synchronizing conveyer in advance of'the conon said synchronizing conveyer for causingdeceleration 40 at'a'contlrolled :rate ofisaid synchronizing-conveyer, and

means controlled by the continuously moving conveyer according to the position of the selected location for initiating anaccelerationcycle to acceleratethe synchronizing conveyer to the speed. of the continuously moving conveyer to'transfer the article to theseleeted location on F the continuously moving conveyer.

3; Apparatus for positioning articles at selected locations on a, continuously moving conveyer element comprising a: synchronizing conveyer in advance of the continuously moving ,conveyer, means actuated byflan article 503cm said; synchronizingrconveyer for causing deceleration of said synchronizing conveyer, and meanscontrolled by the continuously movingconveyer according to the position of the selectedilocation for arresting deceleration'of said synchronizing oonveyerand,initiatingacceleration of ;;the- SYIIChIQIIiZiIigICOIIVQYfiI' after a timedelay correspondvelocityiof the-synchronizing conveyer at which deceleration is arrested.

4. Apparatus -for positioningartioles at selected'loca {tions ;on a continuously 7 moving conveyer element-oomprising ai ynchi'onizing conveyer in advance of the con tinuously moving conveyer, means actuatedby an article on said synchronizing conveyer for causingdeceleration tionofithe selected location for,initiatingacceleration of H the synchronizing conveyer aftera time delay directly proportioned to the 7 difference between a minimum velocity V and the velocity {of the synchronizing conveyer at which.

;; deceleration is arrested.

5. Apparatus for positioning articles atselecteid locations on" a continuously moving conveyer element comprising a synchronizing conveyer 'in advance of the continuously movingconveyena speed controller fortvarying v theijvelocitynof .the synchronizing:conveyerebetween a ing to the tdiiference between a minimum-velocity and the minimumvelocity and anraximum velocity corresponding to the velocity of the continuously moving conveyer; means actuated by an article on said synchron-izing conveyer for operating said controller to decelerating said syn chronizing conveyer from saidmaximum velocity, and means controlled by the continuously tmoving conveyer according to the position of "the'selected location for oper-' ating' said controllerto accelerate -said=synchronizingconveyer to said maximum velocity after a time =delaycn'ie spending to the difference between the minimum velocity"v and the velocity of said synchronizing conveyer at which deceleration is arrested. 7

6. Apparatus for positioning articles" atselected locations on a continuously moving conveyer element comprising a= synchronizing 'conveyer in advance" of i the a continuously moving conveyer, power means for driving said synchronizing conveyer, a -speed control -for said-power means to vary -"'the 'speedof said synchronizing conveyer between a maximum velocity corresponding to the velocity of the continuously-moving.conveyer anda minimum velocity, a first fluid actuated pistonfornperating said speed controller to decelerate said synchronizing conveyer from saidmaxim'um velocity, a second fluid actuated piston for operating said speed controller to accelerate said synchronizing conveyer, means actuated by an article on said 1 synchronizing. conveyer for supplying a metered flow o f-fiuid to-said first piston for operatingsaid-controller to decelerate the synchronizing conveyerfrom; said maximum velocity and for shifting said second iluid actuated piston to its-minimum velocity position,- and-means--actuated accordingto the-position of a selected location on the continuously moving-conveyer for discontinuing the fiowofi-fluidtosaid-first piston andsupplying. a metered flow I of fluid --to said second piston for moving said second piston from its minimum velocity." position -to operate saidspeed -controllerwhen-said se'c-- 0nd piston is moved to a position corresponding to the velocity at which deceleration was arrested and 4 accelerating saidsynchronizing: conveyer to saidmaximum velocityv r 7; Apparatus for positioningl articles at selected loca* tions on acontinuously movingiconveyer element' comprisingla: synchronizing conveyer-'in"--advance of the continuously:movingzconveyerg signal generating Lmeans'ac tuated synchronously with zthe continuously moving'i conveyer=according to theposition'ofa selected location on the con-tinuously; moving conveyer with-respect to the discharge "end of the synchronizingconveyer;Ia-- sensing device positionedto he-actuated by articles on said-syn chronizing-'iconveyer, -a speed controller for va'ryin'g Y the I velocity of said :synchronizingcon'veye'r "between a first velocity corresponding to'the velocity of the continuously moving conveyer and a second velocit y, means actuated F by "said sensing "device T responsive to an article v onsaid 1 synchronizing conveyerfol-operating 'said spee'dcontroller to 'd'eclerate said "synchronizing 'conveyerfrom said firstvelocity," and mean's responsive to said' si'gn'al generator for operating said speed controller to' initiate an acceleration-cycle for accelerating said "synchronizing -conveyer to'saidfi'rst ve'locity after a -time delay correspond'- ing' to the difference between a minimum" velocityfand said second velocity at which deceleration-of said synchronizing conveyeris arrested 8; A control system for a movableconvey'er element comprising p'owermeansio'r driving said conveyer ele ment, a" speed controller for varying 'I the "speed "of'the conveyer element between a" minimumvelocity and=a maximum velocity, a sensing device responsive to'an article on the conveyer'ele ment for Operatingsaidspced controllerto decelerate the conveyer element from said maximum velocity, and -a signal generator-for controlling theoperation of-said speedcontroller -to accelerate the conveyer" element-to" said maximumveldcity. after a time delayxcorrespondingto the difference between said 9'; A speed control for a moving-conveyer element comprising a speed coii'troller" for varying the speed of the conveyer element'betweena minimium velocity and a maximum 'velocity, a first fluid actuated pistonfor operating said speed controllerfto-decelerate the conveyer" element from said maximum velocity,v a' secondfiuidactuatedpiston for operating said speed controller' for accelerating*theconveyer element; means actuated by an article-"on the c'onwyi' element for-'supplying'a' metered -flowoffluidto said first p'ist'onfor moving said speedcontroller to decelerate "the conveyer elementfrom said maximum velocity-and formoving said second piston to -its minimum velocity position; and signal generator means foi' dis'contin'uing the flow'ot fluid to said first piston and'supplying' 'anretered fiow of fluid to said second piston for moving said second piston 'fromits minimum velocity position to sh'iftesaid speed controller" to accelerate the conveyer element after a time delay corresponding to the dilference' between said minimum velocity and the velocityat which deceleration is arrested.

10. Apparatus for positioning articles at selected locations on a continuously moving-conveyer element comprisinga synchronizingiconvcyer inadvance' 'otthe contlnuously movingzconveyerg' means actuated by an "article on--sa1d synchronizing icon'vey'er :forcausingz-deceleration' of 5 said synchronizingconveyer; and means controlledby the continuouslyamovingiconveyer according to the" position of-the selectedvlocation on said continuously moving: conveyor for initiating acceleration of 1 the Y syn chronizing: conveyer. aftera= time': delay related I to the velocity/of the? synchronizing I conveyer at "the time when the deceleration of said synchronizing conveyer is tee" 'minated.

11. Apparatus for positionin'g articles at selected loca'- tions on a continuously moving'conveyer element comprising a synchronizingaconveyerwin=advance-eflthe-continuously moving conveyer, a speed controller for varying the velocity of the synchronizing conveyer at a controlled rate, means actuated b'y'an article on the synchronizingconveyer for operating said speedicontroller to vary theveloc'it'y "of said synchronizing conve er rrom a normal velocity corresponding to thet'speed of the continuously moving conveyerto adifi'eint velocity, and

means controlled by the continuously moving conveyer according to the position of the sleeteddoc'ation for-operating said speed controllerto. return the velocity of said synchronizing conveyer to said normal velocity at said controlled rate g'whereby'an article'transferred'from said synchronizing conveyerarrives' on said continuously moving' 'co'nveyer at- 'sai'd selected location,

- 12: Apparatus forpositioning articles at sel'ected loca tions on a'continuously' moving conveyor element hav-" ing means *forf driving said continuously moving conveyor element at a constant-speed, comprising; a variable speed synchronizing conveyor in advance of' the continuously h'iovin'g conveyoigf-first meansoperatively associatedw'ith said synchronizin'g conveyor and controlled i rby 'an' article thereon for varying the" speeds ofisaid syn-" chronizing conveyor at a controlled rate, and second" means bperatively associated with-said "continuously mov ing conveyorand said selected location for overriding the control by "said "first means aadmssurin that when an ';article is' transferred from said synchronizing "conveyor to said continuously moving-"conve or 'said" synchromzing conveyor has a velocityequalto-the constantvelocity of saidcont'inuoulsly inoving conveyor.

Y fnriences citeainthe file or this patent 

6. APPARATUS FOR POSITIONING ARTICLES AT SELECTED LOCATIONS ON A CONTINUOUSLY MOVING CONVEYER ELEMENT COMPRISING A SYNCHRONIZING CONVEYER IN ADVANCE OF THE CONTINUOUSLY MOVING CONVEYER, POWER MEANS FOR DRIVING SAID SYNCHRONIZING CONVEYER, A SPEED CONTROL FOR SAID POWER MEANS TO VARY THE SPEED OF SAID SYNCHRONIZING CONVEYER BETWEEN A MAXIMUM VELOCITY CORRESPONDING TO THE VELOCITY OF THE CONTINUOUSLY MOVING CONVEYER AND A MINIMUM VELOCITY, A FIRST FLUID ACTUATED PISTON FOR OPERATING SAID SPEED CONTROLLER TO DECELERATE SAID SYNCHRONIZING CONVEYER FROM SAID MAXIMUM VELOCITY, A SECOND FLUID ACTUATED PISTON FOR OPERATING SAID SPEED CONTROLLER TO ACCELERATE SAID SYNCHRONIZING CONVEYER MEANS ACTUATED BY AN ARTICLE ON SAID SYNCHRONIZING CONVEYER FOR SUPPLYING A METERED FLOW OF FLUID TO SAID FIRST PISTON FOR OPERATING SAID CONTROLLER TO DECELERATE THE SYNCHRONIZING CONVEYER FROM SAID MAXIMUM VELOCITY AND FOR SHIFTING SAID SECOND FLUID ACTUATED PISTON TO ITS MINIMUM VELOCITY POSITION, AND MEANS ACTUATED ACCORDING TO THE POSITION OF A SELECTED LOCATION ON THE CONTINUOUSLY MOVING CONVEYER FOR DISCONTINUING THE FLOW OF FLUID TO SAID FIRST PISTON AND SUPPLYING A METERED FLOW OF FLUID TO SAID SECOND PISTON FOR MOVING SAID SECOND PISTON FROM ITS MINIMUM VELOCITY POSITION TO OPERATE SAID SPEED CONTROLLER WHEN SAID SECOND PISTON IS MOVED TO A POSITION CORRESPONDING TO THE VELOCITY AT WHICH DECELERATION WAS ARRESTED AND ACCELERATING SAID SYNCHRONIZING CONVEYER TO SAID MAXIMUM VELOCITY. 